Geological Sciences and Geological Engineering, Department ofhttp://hdl.handle.net/1974/7752017-09-26T21:43:06Z2017-09-26T21:43:06ZAn Examination of Structural Constraints on Rockfall Behaviour using LiDAR DataRowe, Emilyhttp://hdl.handle.net/1974/220422017-09-15T13:19:32ZAn Examination of Structural Constraints on Rockfall Behaviour using LiDAR Data
Rowe, Emily
Rockfall hazards along railway corridors in western Canada increase the risk of train derailment, which could lead to loss of life, infrastructure, and environmental damage. In some cases, such rockfalls exhibit pre-failure deformation prior to their detachment from the slope. The goal of this research is to gain an improved understanding of such precursory behaviour, and how it may be affected by the orientation and condition of discontinuity planes constraining rockfall source blocks. This thesis therefore focuses on the nature of rockfall failure mechanisms, explored using remote terrestrial laser scanning (TLS) data.
TLS data was collected at regular 2-3 month intervals at three study sites along the Thompson-Fraser valley in British Columbia, Canada – namely Goldpan, White Canyon, and Mile 109 – from May 2013 to October 2016. A total of 207 rockfalls were identified across all three sites. For each rockfall, the orientation of joints was measured in the post-failure datasets and used to establish a likely failure mechanism. Pre-failure deformation trends were assessed using a roto-translation approach, which expresses the 3-dimensional transformation of a block from one TLS dataset to a successive dataset in terms of translation and rotation components. Rockfalls were classified by their pattern of deformation as well as failure mechanism and it was concluded that toppling blocks are most likely to exhibit detectable translation and rotation deformation using this method.
The pre-failure deformation of blocks at the Goldpan site was also examined using a vector-based method, which measures block movement in a direction normal to the slope. The classification of such blocks by their failure mechanism revealed an apparent linear relationship between rockfall volume and deformation magnitude and duration for toppling and wedge sliding failures, though additional rockfall cases are required to confirm this.
The methods for analyzing pre-failure deformation applied in this research have limitations and uncertainties, which are discussed. This work forms a basis for the analysis of precursory rockfall behaviour, which may be used to assess the likelihood and mechanism of future rockfall events.
The Influence of Secondary Mineral Phase Crystallization on Antimony and Arsenic Mobility in Mine DrainageBorcinova Radkova, Anezkahttp://hdl.handle.net/1974/158812017-08-10T12:20:27ZThe Influence of Secondary Mineral Phase Crystallization on Antimony and Arsenic Mobility in Mine Drainage
Borcinova Radkova, Anezka
Mine waste containing high concentrations of the potentially toxic metalloids antimony (Sb) and arsenic (As) poses a risk for the natural environment since they are toxic to various organisms. To assess this risk, it is necessary to understand the role of mineralogy, particularly the influences of solubility and variable chemical composition of minerals.
The sites selected for this study allow an insight into the Sb behaviour in three different systems: freshly deposited stibnite-containing tailings at Beaverbrook Sb mine (Newfoundland), historical mine waste at Špania Dolina-Piesky (Slovakia) where tetrahedrite is the main Sb host, and several historical Sb deposits in Slovakia where the Sb association with colloids was investigated. Water analyses using ICP-AS-OS, HG -AAS were combined with mineralogical analyses conducted using a combination of SEM, EMPA, MLA and synchrotron-based μXRD, μXRF and μXANES (see the list of abbreviations).
The study of tetrahedrite weathering reveals that after being released from primary tetrahedrite, Sb becomes a part of a structure of secondary Sb minerals tripuhyite and pyrochlore which are stable in near-surface conditions, whereas As and Cu are contained in µXRD-amorphous phase. It is concluded that Sb is not very mobile when tetrahedrite is weathering under oxidizing, near-neutral conditions.
At Beaverbrook, Sb is rapidly released from stibnite in tailings deposits to the pore water in an oxic environment where it transforms to highest oxidation state Sb5+. Arsenopyrite oxidizes less rapidly, and the formation of oxidation rims contributes to its slower dissolution. The formation of less soluble Sb-Fe secondary phases, and formation and dissolution of easily soluble brandholzite contribute to Sb cycling in the environment of freshly deposited tailings.
In mine drainage from several historical mine sites, it was determined that colloids influence As mobility more than Sb mobility. At the sites where As is the main contaminant, abundant Fe-As-Si-O colloids were detected on the surface of 0.01 µm filters. Only very high Sb concentration (above 6600 µg/L) promoted precipitation of low amounts of Fe-Sb-Si-O±S colloids.
Secondary Sb minerals with different stability are formed in mine waste environment. Understanding the conditions of their formation and their characteristics allow the prediction of potential environmental issues.
PETROGENESIS AND METALLOGENESIS OF THE ULTRAMAFIC LAYERED NORTH LAC DES ILES INTRUSION IN THE LAC DES ILES COMPLEX, ONTARIO, CANADANgue Djon, Moisehttp://hdl.handle.net/1974/158802017-08-10T12:20:27ZPETROGENESIS AND METALLOGENESIS OF THE ULTRAMAFIC LAYERED NORTH LAC DES ILES INTRUSION IN THE LAC DES ILES COMPLEX, ONTARIO, CANADA
Ngue Djon, Moise
A detailed petrologic and metallogenic study was conducted on the eastern flank of the Northern Ultramafic Centre (NUC) of the North Lac des Iles Complex (North LDIC) to understand the petrogenesis of cyclically layered ultramafic cumulates and the processes involved in the formation of the PGE mineralization. Additional investigation of historical PGE-Cu-Ni prospects in the North LDIC provides insights into the styles of mineralization and how these styles compare with the stratiform PGE mineralization of the NUC and the Pd deposits hosted by the mafic Mine Block Intrusion of the South Lac des Iles Complex (South LDIC).
Field relationships, mineralogical, textural, mineral chemical, and lithochemical data from the NUC reveal the presence of two distinct paragenetic sequences of cumulate rocks. Cyclic Unit A (CUA) is characterized by an upward progression of Ol+Cr-SpOl+Opx+Cpx±Cr-SpCpx+Opx Pl+Opx±Cpx. Cyclic Unit B (CUB) exhibits a cumulate stratigraphic progression of Ol+Cr-SpOl+Cpx. CUA sequences are interpreted to have formed by fractional crystallization of more siliceous ultramafic magmas relative to CUB parent magmas.
Stratiform PGE mineralization of the Sutcliffe Zone is typically hosted within four different CUA units. PGE mineralization is commonly associated with >2% disseminated Cu-Ni sulfide, and is characterized by mantle-like S/Se ratios, Pd tenors in sulfide <1000 ppm, and Pd/Pt ratios < 5. The Sutcliffe Zone is interpreted to have formed by a combination of fractional crystallization and dynamic recharge and mixing of CUA and CUB parental magmas.
The majority of PGE-Cu-Ni prospects in the North LDIC share similar host rocks, sulfide and platinum group mineral compositions and textures, trace element signatures, Pd tenors, S/Se and Pd/Pt ratios as the stratiform PGE mineralization at Sutcliffe Zone, similar genesis.
Similarities between stratiform PGE-Cu-Ni mineralization in the North LDIC and the magmatic breccia-style Pd mineralization in the South LDIC include the prevalence of orthopyroxene, widespread magmatic alteration, low sulfide content, Pd-rich PGE mineralization and the dominance of Pd-bismuthotellurides. Despite these similarities, the two styles of mineralization remain distinct in terms of structural controls on mineralization, host rocks, base metal sulfide and PGE mineralogy, PGE tenors of sulfide, and the source of parental magmas.
Origin of Visean (Mississippian) Frobisher Group Coated Grainstone Shoals in the Williston Basin: Deposition and DiagenesisPollard, Alexanderhttp://hdl.handle.net/1974/158642017-08-10T12:20:27ZOrigin of Visean (Mississippian) Frobisher Group Coated Grainstone Shoals in the Williston Basin: Deposition and Diagenesis
Pollard, Alexander
The Frobisher Beds of southeastern Saskatchewan are part of an extensive conventional oil and gas play hosted in grainy carbonate rocks, long interpreted as marine oolites. This sedimentological and diagenetic study of core from the Frobisher in the Bryant and Pinto areas of southeastern Saskatchewan concludes that the ubiquitous coated grains in these rocks are in fact predominantly pedogenically modified rather than purely marine in origin. Areally, Frobisher grainstones form elongate finger-like carbonate sand bodies, persistently supratidal, separated by interpreted marine channel deposits. These shoals consist of numerous stacked shallowing-upward, cyclical deposits composed of peloids, coated grains and compound grains. Unmodified true marine ooids are a minor component. Units within paleochannels consist of allochems of open marine origin and lack the cyclicity seen in shoal units. The Frobisher succession consists of six facies: 1) Fenestral Peloid Packstone, 2) Peloid Coated Grain Grainstone, 3) Coated Grain Grainstone-Rudstone, 4) Multiple Crust Complex, 5) Argillaceous Mudstone/Wackestone, and 6) Skeletal Packstone-Grainstone/Rudstone with variable oolite. Facies 1 to 5 are found within shoal units, whereas Facies 6 occurs only in the channel deposits. Grains within Facies 2 and 3 display shrinkage cracks, inverse grading and irregular coatings, features which are common indicators of pedogenesis in a vadose environment. Mudstones of Facies 5 and complex crust horizons in Facies 4 suggest that the shoal was subject to early diagenetic alteration in an arid subaerial environment. In contrast, Facies 6 contains broken and abraded open marine allochems (bryozoans, crinoids, coral fragments and foraminifera) interpreted to have been deposited and transported in marine channels. Coated grain lithoclasts within the channel deposits suggest active erosion of the finger-like shoals, whereas well ordered ooids-pisoids on the shoals may have originated in the marine channels. These observations demonstrate that there is an alternative interpretation to the published subtidal ooid sand shoal model. In this revised interpretation each shoal cycle shallows up from a thin marine or restricted peritidal facies at the base to grainstones and rudstones of coated grains and complex carbonate crusts, interpreted as a paleo calcrete. Such pedogenic alteration is characteristic of an arid climate and occurred during base level falls which exposed the shoals, and occasionally the intervening channels.